Process for the preparation and use of flame retardant, self-repairable epoxy or polyurethane based composite coatings

Abstract

The application relates to the technical field of functional materials, and discloses a preparation method and application of an epoxy-based or polyurethane-based composite coating with fire resistance and self-repairing functions. The epoxy-based or polyurethane-based composite coating is prepared from epoxy resin or hydroxyl acrylic resin, a curing agent and a functional filler. The functional filler comprises a composite of a calcium-aluminum-based, magnesium-aluminum-based or zinc-aluminum-based hydrotalcite intercalated with an intercalating agent and graphene oxide, a composite of polyethylene imine grafted graphene oxide and aluminum hypophosphite and tung oil microcapsules. The two fillers with fire resistance and the tung oil microcapsules with self-repairing function are compounded, the prepared coating has good adhesion to a substrate, has excellent characteristics such as self-repairing function, fire resistance and thermal stability, can be used for corrosion protection of metal materials, can realize self-repairing, saves manual maintenance cost, is used in the field of coating protection, and can be applied to the field of building material fire prevention as a fireproof material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional materials, in particular to a preparation method and application of a flame-retardant and self-repairable epoxy-based or polyurethane-based composite coating. BACKGROUND

[0002] Corrosion can easily cause damage and aging of equipment, pollute the environment and cause public hazards, and even lead to poisoning, fire, explosion and other serious accidents. In recent decades, organic coating technology has become the preferred method for protecting materials from corrosion and preventing materials from burning because of its easy operation, good adhesion, ability to form a shielding layer between the underlying substrate and the contacting medium, and the like. Among them, epoxy-based coatings are widely welcomed due to their superior mechanical properties, strong adhesion to metal surfaces, excellent water and chemical resistance, strong adhesion, and room temperature operation. Epoxy-based composite coatings can usually well protect the underlying material from damage, but in long-term use, micro-cracks or damage may occur in the coating, and after the substrate is exposed to a corrosive and burning environment, the protective effect of the coating will be significantly reduced.

[0003] CN2202310343936.3 discloses a preparation method of a self-repairing hydrogel flame-retardant coating. Due to specific dynamic reversible hydrogen bonds and borate ester bonds, the hydrogel flame-retardant coating can regenerate and self-repair the three-dimensional structure, and the composite flame-retardant hydrogel coating contains a carbon source, an acid source, a gas source, and a nano synergistic flame retardant, forming a synergistic intumescent flame-retardant system. The self-repairing hydrogel exhibits good self-repairing and flame-retardant properties. CN202211329784.3 discloses a flame-retardant coating with self-repairing and recyclable properties, as well as a preparation method and application thereof. The flame-retardant hydrogel has good self-repairing ability and recyclable and reworkability. However, these intrinsic self-repairing materials mainly use reversible chemical reactions of molecular structures to achieve self-repairing, which often have complex and difficult preparation processes, high raw material costs, high requirements for the materials themselves, and limited applications, which are not suitable for industrial production.

[0004] CN201911304175.0 discloses a flame-retardant microcapsule, a preparation method and application thereof. The double-coated self-repairing flame-retardant microcapsule designed in this patent has a stable double-layer capsule wall and a flame-retardant capsule core, can achieve self-repairing before ignition and flame-retardant effect after ignition, and has dual functions of self-repairing and flame-retardant. However, this double-coated structure has high requirements for the capsule core and capsule wall materials, and may also affect the release of the flame retardant, thereby affecting the flame-retardant effect.

[0005] CN202111260552.2 discloses a room temperature self-repairing water-based transparent intumescent fireproof coating and a preparation method thereof. The patent requires additional addition of a film-forming aid in the base resin, and the self-repairing effect is achieved after the release of the microcapsule core material and the action of the film-forming aid. The content of the intumescent flame retardant added in the coating is as high as 20% to 30%.

[0006] Therefore, there is an urgent need to develop a protective coating with multiple functions such as corrosion resistance, self-repairing, and flame retardation, which is suitable for industrial production. SUMMARY

[0007] The purpose of the present application is to overcome the problems existing in the prior art and provide a preparation method and application of an epoxy-based or polyurethane-based composite coating which is flame-retardant and self-repairable.

[0008] To achieve the above-mentioned purpose, the first aspect of the present application provides an epoxy-based or polyurethane-based coating composition, wherein the composition comprises the following components: epoxy resin or hydroxy acrylic resin, curing agent and functional filler.

[0009] The functional filler comprises a first functional filler, a second functional filler and a third functional filler.

[0010] The first functional filler is a composite of calcium-aluminum-based, magnesium-aluminum-based or zinc-aluminum-based hydrotalcite intercalated with an intercalation agent and graphene oxide; the intercalation agent is selected from at least one of 8-hydroxyquinoline, sodium dodecylbenzenesulfonate and sodium dodecyl sulfate.

[0011] The second functional filler is a composite of polyethyleneimine-grafted graphene oxide and aluminum hypophosphite.

[0012] The third functional filler is tung oil microcapsule.

[0013] The second aspect of the present application provides an epoxy-based or polyurethane-based composite coating prepared from the composition of the first aspect.

[0014] The third aspect of the present application provides a preparation method of the epoxy-based or polyurethane-based composite coating of the second aspect, wherein the method comprises the following steps:

[0015] (1) dissolving the first functional filler, the second functional filler and the third functional filler in an organic solvent to obtain a mixed solution;

[0016] (2) adding epoxy resin or hydroxy acrylic resin and curing agent to the mixed solution obtained in step (1), and obtaining the epoxy-based or polyurethane-based composite coating after curing.

[0017] The fourth aspect of the present application provides the application of the epoxy-based or polyurethane-based composite coating of the second aspect or the epoxy-based or polyurethane-based composite coating prepared by the method of the third aspect in the fireproofing of building materials and the corrosion protection and self-repairing of non-metallic or metallic materials.

[0018] By the above technical solution, the present application has the following beneficial technical effects:

[0019] The present application compounding two fillers with fire-retardant function and tung oil microcapsules with self-repairing function, the prepared coating has good adhesion to the substrate, has excellent properties such as self-repairing, fire-retardant and thermal stability, can be used not only for corrosion protection of metallic materials, but also for self-repairing, saving labor maintenance cost, used in coating protection field, and can be used as fire-retardant material in building material fireproof field. The preparation process is simple, the cost is low, and it has important significance in the fields of corrosion protection, self-repairing and fire-retardant. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 (a) scanning electron microscope image of the tung oil microcapsule in Example 1 of the present application; and (b) optical microscope photograph of the epoxy-based composite coating;

[0021] Figure 2 (a) scanning electron microscope image of the tung oil microcapsule in Example 1 of the present application; and (b) optical microscope photograph of the epoxy-based composite coating;

[0022] Figure 3 (a) scanning electron microscope image of the tung oil microcapsule in Example 1 of the present application; and (b) optical microscope photograph of the epoxy-based composite coating; DETAILED DESCRIPTION

[0023] The endpoints of the ranges and any values claimed herein are not to be understood as being limited to the exact values recited as implicitly disclosed by the above description. Ranges can be expressed as from one "first" value and / or to one "second" value. When such a range is recited, it is to be understood that the range is inclusive of the recited first and second values and that the recited range is not exclusive of other similar values or interstitial values. The endpoints of the ranges and any value between the recited first and second values are specifically encompassed within the range.

[0024] The first aspect of the present application provides an epoxy-based or polyurethane-based coating composition, wherein the composition comprises the following components: epoxy resin or hydroxyl acrylate resin, curing agent and functional filler;

[0025] The functional filler comprises a first functional filler, a second functional filler and a third functional filler.

[0026] The first functional filler is a composite of calcium-aluminum-based, magnesium-aluminum-based or zinc-aluminum-based hydrotalcite intercalated by an intercalating agent and graphene oxide; the intercalating agent is at least one selected from 8-hydroxyquinoline (8-HQ), sodium dodecyl benzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS);

[0027] The second functional filler is a composite of polyethyleneimine grafted graphene oxide and aluminum hypophosphite;

[0028] The third functional filler is tung oil microcapsule.

[0029] For example, the composite of 8-hydroxyquinoline intercalated calcium-aluminum hydrotalcite and graphene oxide is represented as CaAl-8HQ LDH@GO, which is the structure of 8-hydroxyquinoline intercalated calcium-aluminum hydrotalcite coated graphene oxide. The composite of polyethyleneimine grafted graphene oxide and aluminum hypophosphite is represented as PEI-GO@AHP, which is the structure of polyethyleneimine grafted graphene oxide coated aluminum hypophosphite.

[0030] The first functional filler (such as CaAl-8HQ LDH@GO) and the second functional filler PEI-GO@AHP in the present application have a flame-retardant function, can make the coating obtain a higher flame-retardant effect in a small amount of addition, and have good protective performance, thermal stability and flame retardancy.

[0031] The core material of the tung oil microcapsule in the present application is tung oil, which belongs to vegetable oil and can undergo cross-linking and curing reaction with oxygen, has fast film formation and is green and environmentally friendly. The microcapsule has uniform particle size, good dispersibility, high coating rate and good repair effect.

[0032] The first functional filler and the second functional filler with flame-retardant function and the tung oil microcapsule with self-repairing function are compounded as functional fillers in the present application, applied in an epoxy or polyurethane matrix, and simultaneously realize the effects of corrosion prevention, self-repairing and flame retardation.

[0033] In some embodiments of the present application, the mass of the first functional filler and the second functional filler accounts for 0.6-10% of the total mass of the epoxy resin or hydroxy acrylic resin and the curing agent, for example 0.6%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, and any value within the range composed of any two of the above values.

[0034] In some embodiments of the present application, the mass of the third functional filler accounts for 5-20% of the total mass of the epoxy resin or hydroxy acrylic resin and the curing agent, for example 5%, 8%, 10%, 12%, 14%, 15%, 17%, 18%, 20%, and any value within the range composed of any two of the above values.

[0035] In some embodiments of the present application, the mass ratio of the curing agent to the epoxy resin or the hydroxyl acrylic resin is 2:1.

[0036] In some embodiments of the present application, the mass ratio of the first functional filler, the second functional filler and the third functional filler is 1-2:1-2:1-5, for example, 1:1:1, 1:1:3, 1:1:5, 1:2:5, 2:1:5, and any value within the range of any two of the above values.

[0037] In some embodiments of the present application, the tung oil microcapsule has tung oil as the core material and urea-formaldehyde resin as the wall material.

[0038] In some embodiments of the present application, the mass ratio of the core material to the wall material is 0.5-2:1.

[0039] The second aspect of the present application provides an epoxy-based or polyurethane-based composite coating prepared from the composition of the first aspect.

[0040] The epoxy-based or polyurethane-based composite coating provided by the present application has multiple functions such as corrosion resistance, self-repairing, and flame retardation.

[0041] The third aspect of the present application provides a preparation method of the epoxy-based or polyurethane-based composite coating of the first aspect, wherein the method comprises the following steps:

[0042] (1) dissolving the first functional filler, the second functional filler and the third functional filler in an organic solvent to obtain a mixed solution;

[0043] (2) adding the epoxy resin or the hydroxyl acrylic resin and the curing agent to the mixed solution obtained in step (1), and obtaining the epoxy-based or polyurethane-based composite coating after curing.

[0044] In some embodiments of the present application, the organic solvent is selected from at least one of toluene, xylene, n-butanol and acetone.

[0045] In some embodiments of the present application, the mixed solution in step (1) is subjected to ultrasonic treatment.

[0046] In some embodiments of the present application, the mixed solution in step (1) is subjected to ultrasonic treatment.

[0047] In some embodiments of the present application, the ultrasonic treatment is performed under the following conditions: ultrasonic power of 50-150 kW and ultrasonic time of 10-30 min.

[0048] In some embodiments of the present application, after the curing agent is added, the mixture is stirred for 15 min.

[0049] In some embodiments of the present application, the conditions for the curing include: a curing temperature of 35°C; and a curing time of 2-5 days.

[0050] In some embodiments of the present application, the method for preparing the first functional filler includes: mixing a solution containing graphene oxide and intercalation agent with a solution containing one of calcium nitrate, magnesium nitrate or zinc nitrate and aluminum nitrate, and reacting to obtain a composite of intercalation agent intercalated calcium-aluminum based, magnesium-aluminum based or zinc-aluminum based hydrotalcite and graphene oxide.

[0051] In some embodiments of the present application, the solution containing graphene oxide and intercalation agent is stirred at 45°C for 40 min.

[0052] In some embodiments of the present application, the mixing time is 1 h.

[0053] In some embodiments of the present application, the conditions for the reaction include: a pH of 10-10.5; a temperature of 120°C; and a time of 24 h. The reaction can be carried out in a high-pressure kettle with NaOH as a pH adjuster.

[0054] According to a particularly preferred embodiment of the present application, the method for preparing the first functional filler CaAl-8HQ LDH@GO includes:

[0055] (1) mixing 20 mL of graphene oxide solution (0.5 mg / mL) with 0.50 g of 8-HQ in 20 mL of deionized water, and stirring at 45°C for 40 min to obtain a first mixed solution;

[0056] (2) pouring the first mixed solution into solution A, adjusting the pH to 10-10.5, and stirring for 1 h under a nitrogen atmosphere to obtain a second mixed solution; solution A is prepared by continuously stirring 0.30 M Ca(NO3)2·4H2O and 0.10 M Al(NO3)3·9H2O in 60 mL of pure water at 80°C;

[0057] (3) pouring the second mixed solution into a high-pressure kettle, treating at 120°C for 24 h, then centrifuging at 3800 rpm for 25 min, rinsing with deionized water and ethanol until the pH becomes neutral, and drying to obtain CaAl-8HQ LDH@GO.

[0058] In some embodiments of the present application, the method for preparing the second functional material includes: adding a graphene oxide solution to a solution of polyethyleneimine to obtain a solution of polyethyleneimine grafted graphene oxide; and first mixing the solution with a solution of aluminum hypophosphite to obtain a composite of polyethyleneimine grafted graphene oxide and aluminum hypophosphite.

[0059] The solution of the polyethyleneimine grafted graphene oxide can be obtained by mixing a solution of polyethyleneimine and a solution containing 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide, adding graphene oxide solution to the mixture, stirring for 24 hours, and removing unreacted polyethyleneimine by dialysis.

[0060] In some embodiments of the present application, the first mixing time is 15 min.

[0061] In some embodiments of the present application, the product after the first mixing is filtered to obtain a precipitate, and the precipitate is freeze-dried and ground to obtain the composite.

[0062] In some embodiments of the present application, the freeze-drying time is 24 h.

[0063] In some embodiments of the present application, the solution of polyethyleneimine and the solution containing 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide are mixed, and then graphene oxide solution is added to obtain a dispersion.

[0064] In some embodiments of the present application, the mass ratio of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride to N-hydroxysuccinimide is 1:0.1-1.

[0065] In some embodiments of the present application, the stirring time is 24 h to obtain the dispersion.

[0066] According to a particularly preferred embodiment of the present application, the preparation method of the second functional filler comprises:

[0067] (1) mixing a solution of polyethyleneimine and a solution containing 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide, adding 300 mL of graphene oxide (1 mg / mL GO) dispersion dropwise to the above solution, then stirring the mixture at room temperature for 24 h, and finally removing unreacted PEI by dialysis to obtain PEI grafted GO (PEI-GO);

[0068] (2) dispersing 40 mg of PEI-GO in 100 mL of deionized water and adding to a solution of aluminum hypophosphite, stirring vigorously for 15 min; then filtering the precipitate, freeze-drying the precipitate for 24 h, and finally grinding to obtain PEI-GO@AHP.

[0069] The solution of polyethyleneimine is prepared by dissolving 2.5 g of polyethyleneimine (PEI) in 250 mL of deionized water.

[0070] A solution containing 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide was prepared by dissolving 3.6 g of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide at a mass ratio of 1:0.1-1 in 300 mL of deionized water.

[0071] The solution of aluminum hypophosphite described above was prepared by dispersing 4 g of aluminum hypophosphite (AHP) in 50 mL of deionized water.

[0072] In some embodiments of the present application, the preparation method of the third functional filler comprises: reacting a reaction solution of urea and formaldehyde, an emulsion containing tung oil and an emulsifier, resorcinol and ammonium chloride to obtain tung oil microcapsules. The above method is an in-situ polymerization method.

[0073] In some embodiments of the present application, the molar ratio of urea and formaldehyde is 1:1.6-2; the reaction temperature is 70°C; the reaction time is 30-60 min; and the pH of the reaction solution is 8-9.

[0074] In some embodiments of the present application, the emulsifier is at least one selected from the group consisting of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, polyvinyl alcohol, OP-10, Span-80, Tween-80 and Tween-20.

[0075] In some embodiments of the present application, the conditions for forming the emulsion comprise: an emulsification rotation speed of 500-5000 rpm; and an emulsification time of 30-60 min.

[0076] In some embodiments of the present application, the reaction conditions comprise: a reaction temperature of 50-70°C; and a reaction time of 3-5 h.

[0077] According to a particularly preferred embodiment of the present application, the preparation method of the third functional filler comprises:

[0078] (1) dissolving urea in a formaldehyde solution, stirring and reacting at 70°C for 30-60 min to obtain a solution; wherein the molar ratio of urea and formaldehyde is 1:1.6-2, and the pH of the solution is controlled to be 8-9;

[0079] (2) mixing tung oil, an emulsifier and water, and emulsifying at 500-5000 rpm for 30-60 min to obtain an emulsion;

[0080] (3) adding the solution of step (1), resorcinol and ammonium chloride to the emulsion of step (2), adjusting the pH to 2-5, and reacting at 50-70°C for 3-5 h; after the reaction is completed, cooling, suction filtration, washing and drying to obtain tung oil microcapsules.

[0081] The emulsifier in step (2) is at least one selected from sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, polyvinyl alcohol, OP-10, Span-80, Tween-80 and Tween-20.

[0082] The fourth aspect of the present application provides the application of the epoxy-based or polyurethane-based composite coating prepared by the method of the third aspect in the fireproofing of building materials and the corrosion protection and self-repairing of non-metallic or metallic materials.

[0083] The present application will be described in detail below through examples.

[0084] In the following examples and comparative examples, the specific conditions not specified are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be obtained by market purchase.

[0085] Example 1

[0086] This example provides a method for preparing an epoxy-based composite coating, and the specific steps are as follows:

[0087] I. Preparation of CaAl-8HQ LDH@GO:

[0088] (1) 20 mL of graphene oxide solution (0.5 mg / mL) was mixed with 0.50 g of 8-HQ in 20 mL of deionized water, and stirred at 45°C for 40 min to obtain a first mixed solution;

[0089] (2) The first mixed solution was poured into solution A, and the pH was adjusted to 10, and stirred in a nitrogen atmosphere for 1 h to obtain a second mixed solution; solution A was prepared by continuously stirring 0.30 M Ca(NO3)2·4H2O and 0.10 M Al(NO3)3·9H2O in 60 mL of pure water at 80°C;

[0090] (3) The second mixed solution was poured into an autoclave and treated at 120°C for 24 h, then centrifuged at 3800 rpm for 25 min, washed with deionized water and ethanol until the pH became neutral, and dried to obtain CaAl-8HQ LDH@GO.

[0091] II. Preparation of PEI-GO@AHP:

[0092] (1) 2.5 g of polyethyleneimine (PEI) was dissolved in 250 mL of deionized water to obtain a polyethyleneimine solution; 3.6 g of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide were dissolved in 300 mL of deionized water at a mass ratio of 1:1 to obtain a solution containing 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide; 4 g of aluminum hypophosphite (AHP) was dispersed in 50 mL of deionized water to obtain an aluminum hypophosphite solution;

[0093] (2) After mixing the polyethyleneimine solution and the solution containing 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide, 300 mL of graphene oxide (1 mg / mL GO) dispersion was added dropwise to the above solution, and then the mixture was stirred at room temperature for 24 h. Finally, the unreacted PEI was removed by dialysis to obtain PEI-grafted GO (PEI-GO);

[0094] (3) 40 mg of PEI-GO was dispersed in 100 mL of deionized water and added to the aluminum hypophosphite solution, and stirred vigorously for 15 min; then the precipitate was filtered and freeze-dried for 24 h, and finally ground to obtain PEI-GO@AHP.

[0095] III. Preparation of tung oil microcapsules:

[0096] (1) Urea was dissolved in formaldehyde solution and stirred at 70°C for 30 min to obtain a solution; the molar ratio of urea to formaldehyde was 1:1.6, and the pH of the solution was controlled at 8;

[0097] (2) Tung oil, sodium dodecyl sulfate and water were mixed and emulsified at 1000 rpm for 40 min to obtain an emulsion;

[0098] (3) The solution of step (1), resorcinol and ammonium chloride were added to the emulsion of step (2), the pH of the emulsion was adjusted to 3, and the reaction was carried out at 60°C for 4 h. After the reaction was completed, the mixture was cooled and filtered, washed and dried to obtain tung oil microcapsules.

[0099] IV. Preparation of epoxy-based composite coating by mechanical stirring method:

[0100] (1) CaAl-8HQ LDH@GO, PEI-GO@AHP and tung oil microcapsules were dispersed in 1.2 g of toluene solvent, and the mass ratio of the three functional fillers was 1:1:1. The mass of CaAl-8HQ LDH@GO and PEI-GO@AHP accounted for 10% of the total mass of epoxy resin and curing agent, and the mass of tung oil microcapsules accounted for 5% of the total mass of epoxy resin and curing agent; then ultrasonic treatment was carried out for 30 min;

[0101] (2) 2 g of epoxy resin (E44) was injected into the mixture prepared in step (1), and ultrasonic vibration was performed for 15 min;

[0102] (3) A curing agent was added in a mass ratio of 2:1 to the epoxy resin, mixed with the epoxy resin, stirred for about 15 min, and coated on a Q235 carbon steel substrate to form an epoxy-based composite coating after curing at 35℃ for 2 days.

[0103] Example 2

[0104] The preparation method of this example is the same as described in Example 1, except that the mass ratio of the three functional fillers is 1:1:3 when preparing the epoxy-based composite coating.

[0105] Example 3

[0106] The preparation method of this example is the same as described in Example 1, except that the mass ratio of the three functional fillers is 1:1:5 when preparing the epoxy-based composite coating.

[0107] Example 4

[0108] The preparation method of this example is the same as described in Example 1, except that the mass ratio of the three functional fillers is 1:2:5 when preparing the epoxy-based composite coating.

[0109] Example 5

[0110] The preparation method of this example is the same as described in Example 1, except that the mass ratio of the three functional fillers is 2:1:5 when preparing the epoxy-based composite coating.

[0111] Example 6

[0112] The preparation method of this example is the same as described in Example 5, except that 8-HQ is replaced by SDS.

[0113] Example 7

[0114] The preparation method of this example is the same as described in Example 5, except that 8-HQ is replaced by SDBS.

[0115] Example 8

[0116] The epoxy resin (E44) in Example 5 was replaced by a hydroxyl acrylate resin (FX-9012), and a fatty isocyanate (Bayer N3390) was selected as the curing agent to prepare a polyurethane-based composite coating.

[0117] Comparative Example 1

[0118] This comparative example provides a method for preparing a pure epoxy coating, the specific steps are as follows:

[0119] (1) 2 g of epoxy resin (E44) was added to 1.2 g of toluene and stirred for 15 min under ultrasonic;

[0120] (2) The curing agent was added at a mass ratio of 2:1 to the epoxy resin, mixed with the epoxy resin for about 15 min, and coated on a Q235 carbon steel substrate to form an epoxy-based coating layer after curing at 35°C for 2 days.

[0121] Test Example 1

[0122] Figure 1 The SEM image of the tung oil microcapsules prepared in Example 1 and the OM image of the epoxy-based composite coating layer are shown, which shows that the tung oil microcapsules have a smooth and compact surface, a regular morphology, and a uniform particle size, and can be uniformly dispersed in the epoxy-based composite coating layer.

[0123] Figure 2 The SEM images of the self-repairing effect of the pure epoxy-based coating layer prepared in Comparative Example 1 and the epoxy-based composite coating layers prepared in Examples 1-3 after scratching for 24 h are shown. It can be seen that Figure 2 When the coating layer is scratched with a small knife, the microcapsules around the scratch break due to external stress, the tung oil inside flows out, contacts with oxygen in the air, and undergoes crosslinking polymerization reaction, thereby realizing self-repairing. As the content of microcapsules gradually increases, the crack area of the coating layer becomes smaller, indicating that the self-healing effect is better.

[0124] Test Example 2

[0125] After the coating layers of Comparative Example 1 and Examples 1-6 were immersed in a 3.5% sodium chloride solution for 1 day, the impedance value of each coating layer at 0.01 Hz was tested by electrochemical impedance method, as shown in Figure 3 .

[0126] Compared with the pure epoxy coating layer in Comparative Example 1, the impedance values of the epoxy-based composite coating layers with functional fillers are obviously improved, which is because the nano-functional fillers added in the epoxy coating layer are uniformly distributed, which gives the epoxy-based composite coating layer excellent barrier effect and self-healing effect.

[0127] Test Example 3

[0128] The flame retardancy of the coating layers prepared in Examples 1-6 and Comparative Example 1 was evaluated by vertical burning UL-94 and limiting oxygen index (LOI) test.

[0129] Table 1 UL-94 burning test results of the coating layers

[0130]

[0131] As can be seen from Table 1, the LOI of the pure epoxy coating of Comparative Example 1 is 23.7%, and it is completely burned in the vertical burning test, so the sample does not reach any UL-94 rating. After adding the functional filler, the LOI of Example 1 reaches 30.5%, and the sample passes the UL-94 V-0 rating. When the amount of tung oil microcapsules increases, it has a negative impact on the flame retardancy, causing the LOI value to decrease. When the amount of tung oil microcapsules is constant, the two flame retardants are compounded in a certain ratio, and they can also self-extinguish within 4s and pass UL-94 to reach the V-0 level, and the LOI is slightly improved. Under the same filler ratio as Example 5, the LOI of Examples 6 and 7 decreases, indicating that the flame-retardant effect of 8-HQ as an intercalating agent is better than that of SDS and SDBS, and it is more suitable for the entire compounded system. The LOI of the polyurethane of Example 8 is slightly lower than that of the epoxy resin, but it can also reach 28.1%, and the vertical burning test rating can still reach the V-0 level.

[0132] The above describes the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application, and all fall within the protection scope of the present application.

Claims

1. An epoxy- or polyurethane-based coating composition, characterized in that, The composition comprises the following components: an epoxy resin or a hydroxyl acrylic resin, a curing agent and a functional filler; The functional filler comprises a first functional filler, a second functional filler and a third functional filler; The first functional filler is a composite of calcium-aluminum-based, magnesium-aluminum-based or zinc-aluminum-based hydrotalcite intercalated with an intercalation agent and graphene oxide; the intercalation agent is 8-hydroxyquinoline; The second functional filler is a composite of polyethyleneimine grafted graphene oxide and aluminum hypophosphite; The third functional filler is tung oil microcapsule; The mass ratio of the first functional filler, the second functional filler and the third functional filler is 1-2:1-2:1-5; The preparation method of the second functional material comprises the following steps: mixing a solution of polyethyleneimine and a solution containing 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide, then adding a graphene oxide solution to obtain a solution of polyethyleneimine grafted graphene oxide; and mixing the solution with a solution of aluminum hypophosphite to obtain a composite of polyethyleneimine grafted graphene oxide and aluminum hypophosphite.

2. The composition of claim 1, wherein, The mass of the first functional filler and the second functional filler accounts for 0.6-10 % of the total mass of the epoxy resin or the hydroxyl acrylic resin and the curing agent; And / or, the mass of the third functional filler accounts for 5-20 % of the total mass of the epoxy resin or the hydroxyl acrylic resin and the curing agent.

3. The composition of claim 1, wherein, The tung oil microcapsule takes tung oil as a core material and urea-formaldehyde resin as a wall material.

4. The composition of claim 3, wherein, The mass ratio of the core material and the wall material is 0.5-2:

1.

5. An epoxy-based or polyurethane-based composite coating prepared from the composition according to any one of claims 1-4.

6. A process for the production of an epoxy- or polyurethane-based composite coating according to claim 5, characterized in that, The method comprises the following steps: (1) dissolving the first functional filler, the second functional filler and the third functional filler in an organic solvent to obtain a mixed solution; (2) adding an epoxy resin or a hydroxyl acrylic resin and a curing agent to the mixed solution obtained in step (1), and curing to obtain the epoxy-based or polyurethane-based composite coating.

7. The method of claim 6, wherein, The preparation method of the first functional filler comprises the following steps: mixing a solution containing graphene oxide and an intercalation agent with a solution containing one of calcium nitrate, magnesium nitrate or zinc nitrate and aluminum nitrate, and reacting to obtain a composite of calcium-aluminum-based, magnesium-aluminum-based or zinc-aluminum-based hydrotalcite intercalated with the intercalation agent and graphene oxide.

8. The method of claim 7, wherein, The solution containing graphene oxide and the intercalation agent is stirred at 45 ℃ for 40 min; And / or, the mixing time is 1 h; And / or, the reaction conditions comprise: pH is 10-10.5; temperature is 120 ℃, and time is 24 h. The first mixing time is 15 min; 9. The method of claim 6, wherein, And / or, filtering the product after the first mixing to obtain a precipitate, freeze-drying the precipitate and grinding to obtain the composite. The freeze-drying time is 24 h.

10. The method of claim 9, wherein, In the second mixing, the mass ratio of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide is 1:0.1-1.

11. The method of claim 6, wherein, ​ 12. The method of claim 6, wherein, The preparation method of the third functional filler comprises: reacting a reaction solution of urea and formaldehyde, an emulsion containing tung oil and an emulsifier, resorcinol and ammonium chloride to obtain tung oil microcapsules.

13. The method of claim 12, wherein, The molar ratio of urea and formaldehyde is 1:1.6-2; the reaction temperature is 70 DEG C; the reaction time is 30-60 min; the pH of the reaction solution is 8-9; And / or, the emulsifier is selected from at least one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, polyvinyl alcohol, OP-10, span-80, Tween-80 and Tween-20; And / or, the emulsion forming conditions include: the emulsification rotation speed is 500-5000 rpm; the emulsification time is 30-60 min; And / or, the reaction conditions include: the reaction temperature is 50-70 DEG C, and the reaction time is 3-5 h.

14. The application of the epoxy or polyurethane composite coating according to claim 5 or the epoxy or polyurethane composite coating prepared by the method according to any one of claims 6-13 in building material fire retardation and non-metal or metal material corrosion prevention, self-repairing.

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